parts previously defined in <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>. Range requests are an <em class="bcp14">OPTIONAL</em> feature of HTTP, designed so that recipients not implementing this feature (or not supporting it for the target resource)

</pre><p id="rfc.section.2.1.p.11">If the selected representation is shorter than the specified <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, the entire representation is used. For example (assuming a representation of length 10000):

695

</p>

694

</pre><p id="rfc.section.2.1.p.11">If the selected representation is shorter than the specified <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, the entire representation is used.

<p id="rfc.section.2.1.p.12">If a valid <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> includes at least one <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> with a <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> that is less than the current length of the representation, or at least one <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> with a non-zero <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, then the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is satisfiable. Otherwise, the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is unsatisfiable.

710

</p>

711

<p id="rfc.section.2.1.p.13">In the byte range syntax, <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>, <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>, and <a href="#rule.ranges-specifier" class="smpl">suffix-length</a> are expressed as decimal number of octets. Since there is no predefined limit to the length of a payload, recipients ought

710

<p id="rfc.section.2.1.p.13">If a valid <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> includes at least one <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> with a <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> that is less than the current length of the representation, or at least one <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> with a non-zero <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, then the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is satisfiable. Otherwise, the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is unsatisfiable.

711

</p>

712

<p id="rfc.section.2.1.p.14">In the byte range syntax, <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>, <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>, and <a href="#rule.ranges-specifier" class="smpl">suffix-length</a> are expressed as decimal number of octets. Since there is no predefined limit to the length of a payload, recipients ought

712

713

to anticipate potentially large decimal numerals and prevent parsing errors due to integer conversion overflows.

<p> <b>Note:</b> Because servers are free to ignore <a href="#header.range" class="smpl">Range</a>, many implementations will simply respond with <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> if the requested ranges are invalid or not satisfiable. That is partly because most clients are prepared to receive a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> to complete the task (albeit less efficiently) and partly because clients might not stop making an invalid partial request

936

<p> <b>Note:</b> Because servers are free to ignore <a href="#header.range" class="smpl">Range</a>, many implementations will simply respond with the entire selected representation in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response if the requested ranges are invalid or not satisfiable. That is partly because most clients are prepared to receive

937

a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> to complete the task (albeit less efficiently) and partly because clients might not stop making an invalid partial request

936

938

until they have received a complete representation. Thus, clients cannot depend on receiving a <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> response even when it is most appropriate.